Self-diffusion in Sintering of Metallic Particles
Two particles in mutual contact form a system which is not in thermo-dynamical equilibrium, because its total surface free energy is not a minimum. If such a system is left for a certain period of time, the bonding of the two particles will take place in order to decrease the total surface area, even though […]
Placing Concrete in a Deep Mine
In U. S. underground mines concrete work is not widely used. Timber and steel are cheaper, and there are few serious water problems. But in the Union of South Africa men dig deeper, more persistently, and probably more profitably than anywhere else on earth. Some gold mines near Johannesburg are below the 10,000 level and […]
Ball Mill Shell Liner Performance
Grinding Practice—These tests were run in the 9 ft diam by 8 ft long grate discharge ball mills at Climax. Each mill functions in closed circuit with a 78 in. Akins duplex high-weir classifier, and a circulating load of 300 pct is maintained. The size of the mill feed is 6 pct on 3/8ths, which […]
Mine Ore Mining Methods
Iron king mine, producing gold-silver-lead-zinc ore, is 10 miles east of Prescott, Ariz. At present the 1806 level is being developed. The echelon pattern of ore deposit continues at depth but is less pronounced, and the orebody is now more or less continuous over 2600 ft of strike length, with widths 5 ft to as […]
Humphreys Spiral Concentrator
Since it was introduced in 1943 to recover chromite from Oregon beach sands, the Humphreys spiral concentrator has proved successful in several fields of wet mineral beneficiation. By the end of 1957, 9390 Humphreys spirals had been manufactured. Most of these are still in service. Requirements for Spiral Concentration: Valuable heavy minerals to be recovered […]
Mineral Flotation with Ultrasonically Emulsified Collecting Reagents
An emulsion is a two-phase system consisting of two incompletely miscible liquids, the one being dispersed as finite droplets in the other. The dispersed liquid is known as the internal or discontinuous phase, and the surrounding liquid is termed the external or continuous phase. Apparatus and Experimental Procedure: Ultrasonic emulsification was performed in three steps, although […]
Dry Magnetic Cobbing Separation
Cobbing, as used in this paper, refers to coarse dry magnetics separation. It is applicable when, by its practice, plant cost can be reduced or the value of its products increased by the removal of a barren or lean reject or a high grade final product. This paper attempts to describe cobbing as it is […]
Belt Conveyor Design
Idlers: Due to the efforts of the Conveyor Equipment Manufacturers Association, the basic idler elements—idler roll wall thickness, bearing sizes and shaft sizes—have been standardized into classes. There is also a substantial dimensional commonality as well. Belting: Again, the rubber manufacturers have standardized, either by agreement through industry associations, or by following the leader and […]
Aerofall Mill Liner Design
According to the manufacturer, a distinctive feature of the Aerofall mill, as compared to the conventional mill, is the special feature of its wedge shape “deflector” liner design (Figures 2 and 3) which was claimed to provide “keying” action in the mill that produces an important part of the crushing and grinding action in the […]
Contact Angles and Flotation Rate
The object of this article is to point out the experimental relationship which exists among contact angle, adsorption density, zeta potential, and flotation rate data. In each of the experiments discussed in this article, the surface properties of quartz, as a function of pH, were measured in solutions to which constant quantities of dodecylammonium acetate […]